Newly Discovered Extrasolar Planet Is Smallest Yet

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Newly Discovered Extrasolar Planet Is Smallest Yet

European scientists announced the discovery of a terrestrial-type planet only five times the mass of the Earth, making it the smallest exoplanet yet discovered.

The planet, named GJ 436c, orbits a star in the constellation Leo about 30 light years from earth. Because of its different size and position within its solar system, a full day on the planet would translate into three weeks of Earth time.

Scientists have now discovered over 270 planets outside our solar system, and have begun to characterize some of their atmospheres. Most recently, an organic molecule was discovered on a planet 60 light years from earth. But only four exoplanets are anywhere close to the size and composition of Earth. These are referred to as super-Earths.

The researchers even calculate that GJ 436c is very hot, with temperatures in the hundreds of degrees Celsius, however, the poles could get as "cold" as 77 degrees Celsius, which is well-within the thresholds of extremophile bacteria on our planet.

Extrasolar planets are detected by a variety of means, although most often by detecting the gravitational "wobble" in a star caused by the presence of one or more planets. In a first for astronomers, the new planet was detected from perturbations in a previously-known Neptune-like planet's orbit.

"The study opens a new path that should lead to the discovery of even smaller planets in the near future, with the goal of eventually finding worlds more and more similar to the Earth," said Ignasi Ribas, of the Spanish Research Council, in a release.

Image: Courtesy of University College London. The image depicts the two planets in their respective orbits.